A) Bi2O5 is metallic oxide but N2O5 is non metallic oxide therefore Bi2O5 is basic but N2O5 is acidic. B)In NF3, N and F are non metals but BiF3,Bi is metal but F is non metal therefore NF3 is more covalent than BiF3 C) In PH3 hydrogen bonding is absent but in NH3 hydrogen bonding is present therefore PH3 boils at lower temperature than NH3. D) Due to small size in N–N single bond l.p. – l.p. repulsion is more than P–P single bond therefore N–N single bond is weaker than the P–P single bond.